Question

these noble gas electron configurations can be used as a \short cut\. heliums electron configuration is 1s². we can now sub in he into an electron configuration instead of writing out 1s²! helium is not as helpful as the other noble gasses. lets look at magnesium, its electron configuration is 1s² 2s² 2p⁶ 3s². now instead, we can write it as ne 3s²! (not hene 3s². we just write the closest noble gas to the element)
now you try, give the noble gas notation for the following elements:

1. sodium:____
2. phosphorus:____
3. iron:____
4. strontium:____
5. bromine:____
6. oxygen:____
7. argon:____
8. aluminum:____
9. francium:____
10. tellurium:____

challenge question!
write the full electron configuration and noble gas notation for uranium!
electron configuration:____

Explanation:

Step1: Recall noble - gas notation rule

Find the closest noble gas with fewer electrons than the element and write its symbol in brackets, then write the remaining electron configuration.

Step2: Determine noble - gas notation for Sodium (Na, atomic number = 11)

The closest noble gas is Neon (Ne, atomic number = 10). So the noble - gas notation is [Ne]3s¹.

Step3: Determine noble - gas notation for Phosphorus (P, atomic number = 15)

The closest noble gas is Neon (Ne). After Ne, there are 5 more electrons. So the noble - gas notation is [Ne]3s²3p³.

Step4: Determine noble - gas notation for Iron (Fe, atomic number = 26)

The closest noble gas is Argon (Ar, atomic number = 18). After Ar, there are 8 more electrons. So the noble - gas notation is [Ar]3d⁶4s².

Step5: Determine noble - gas notation for Strontium (Sr, atomic number = 38)

The closest noble gas is Krypton (Kr, atomic number = 36). After Kr, there are 2 more electrons. So the noble - gas notation is [Kr]5s².

Step6: Determine noble - gas notation for Bromine (Br, atomic number = 35)

The closest noble gas is Argon (Ar). After Ar, there are 17 more electrons. So the noble - gas notation is [Ar]3d¹⁰4s²4p⁵.

Step7: Determine noble - gas notation for Oxygen (O, atomic number = 8)

The closest noble gas is Helium (He). After He, there are 6 more electrons. So the noble - gas notation is [He]2s²2p⁴.

Step8: Determine noble - gas notation for Argon (Ar, atomic number = 18)

Since it is a noble gas, its noble - gas notation is [Ar].

Step9: Determine noble - gas notation for Aluminum (Al, atomic number = 13)

The closest noble gas is Neon (Ne). After Ne, there are 3 more electrons. So the noble - gas notation is [Ne]3s²3p¹.

Step10: Determine noble - gas notation for Francium (Fr, atomic number = 87)

The closest noble gas is Radon (Rn, atomic number = 86). After Rn, there is 1 more electron. So the noble - gas notation is [Rn]7s¹.

Step11: Determine noble - gas notation for Tellurium (Te, atomic number = 52)

The closest noble gas is Krypton (Kr). After Kr, there are 16 more electrons. So the noble - gas notation is [Kr]4d¹⁰5s²5p⁴.

Step12: Determine electron configuration and noble - gas notation for Uranium (U, atomic number = 92)

The full electron configuration is 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰4f¹⁴5s²5p⁶5d¹⁰5f³6s²6p⁶6d¹7s².
The closest noble gas is Radon (Rn). After Rn, there are 14 more electrons. So the noble - gas notation is [Rn]5f³6d¹7s².

Answer:

1. [Ne]3s¹
2. [Ne]3s²3p³
3. [Ar]3d⁶4s²
4. [Kr]5s²
5. [Ar]3d¹⁰4s²4p⁵
6. [He]2s²2p⁴
7. [Ar]
8. [Ne]3s²3p¹
9. [Rn]7s¹
10. [Kr]4d¹⁰5s²5p⁴

Electron configuration of Uranium: 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰4f¹⁴5s²5p⁶5d¹⁰5f³6s²6p⁶6d¹7s²
Noble - gas notation of Uranium: [Rn]5f³6d¹7s²